Em created digital paintings at the Xerox Palo Alto Research Center (Xerox PARC) in 1975 with SuperPaint, "the first complete digital paint system".[1] In 1976, he made an articulated 3D digital insect at Information International, Inc. (III) that could walk, jump, and fly, the first 3D character created by a fine artist.[2]

Em's art is difficult to categorize. His work spans multiple media, including all-electronic virtual worlds, filmmaking, photography, and printmaking. He has also worked with live performance and theater. [5]Most of his work exists outside of the mainstream art world.

Stylistically, Em's art has connections to Surrealism, abstract painting, and experimental film. There are also often landscape and architectural elements. Some pieces feature geometric components, while others are organic in nature.

He says he "makes pictures with electronic light” and "sculpts with memory instead of space.”[6] He also "evolves images so that they grow into and out of each other” [7]

Some of his early works done at the Jet Propulsion Laboratory in the 1970s have deep-space related themes. In the 1980s he incorporated light effects reminiscent of the French Impressionists,[8] and in the 1990s he introduced otherworldly lifeforms into his work. In the early Twenty-First century, an apocalyptic element appears in his imagery.